Many types of pneumatic and hydraulic fluid couplings have been devised over the years. The purpose of these couplings is to connect and disconnect fluid lines of various types and to conduct fluids at various pressures. Examples of prior art type fluid couplings are found in U.S. Pat. Nos.: 4,723,797; 4,702,278; 4,583,711; 4,543,994; 4,240,466; 4,222,411; 3,831,984; 3,826,523; 3,788,348; 3,758,137; 3,666,300; 3,646,964; 3,592,231; 3,561,472; 3,530,887; 3,498,641; 3,490,491; 3,431,942; 3,163,178; 2,706,646; 2,322,877; 2,318,965; 2,304,390; Re. 27,635.
Although all of the above couplings are improvements over the then existing prior art, there are certain features that are desired for couplings in virtually all applications. One such feature is ease of engagement. In many couplings tools are required to effect connection and disengagement. In other couplings, tools are not required, but it is necessary to manipulate awkward mechanisms before the coupling halves will engage. In other couplings it is necessary to apply excessive pressure to force the couplings together before the coupling halves will engage. Likewise, when it is necessary to disengage the coupling, excessive pressure or awkward manipulations may be required.
Other couplings have the disadvantage that the coupling halves must be aligned in a particular orientation before they will engage. This prevents the coupling halves from swiveling with respect to each other which is often desired in making fluid connections. Other coupling designs have parts that wear out due to repeated coupling and uncoupling as well as the effects of high loading conditions due to the pressure of the fluid carried by the coupling.
It is almost universally desirable that a coupling once connected, be locked together in a reliable fashion and be highly resistant to the leakage of fluid.
Thus there exists a need for a fluid coupling for joining hydraulic or pneumatic fluid lines which may be readily connected and disconnected without awkward manipulations or the use of tools, is capable of being connected in any orientation and swiveling, is positively locked when engaged, is resistent to wear and is inexpensive to produce.